The present invention generally relates to a woven fabric which is rendered endless by interdigitating a plurality of loops which are on the two ends of the fabric. More particularly, it relates to a pintle connector which is inserted through the aligned loops to close the seam. Even more specifically, it relates to a seaming pintle, either solid or hollow, that is expandable after insertion through the aligned loops of a seam to tighten the connection.
Fabrics used on a papermaking machine are often woven open ended so that the ends of the fabric can be joined by a seam to form an endless fabric. A typical seam for a papermakers fabric includes a plurality of loops on each end of the fabric. The loops are generally aligned in an alternating intermeshing relationship to form a channel through which a pintle is inserted to close the seam.
As papermaking machines have developed, machine speeds ranging between four thousand (4,000) and five thousand (5,000) feet per minute have become common. Additionally, papermaking fabrics are maintained under tremendous stress and tension while being used in the forming, press or dryer position on a papermaking machine. As a result of the high speeds and the increased temperature, moisture, and seam pintle strength, as well as increased pressure and operational conditions to which the seam is exposed, surface marking characteristics and wear resistance have become prime considerations. Accordingly, efforts have been made to increase seam strength by increasing the diameter of the pintle. The diameter of the pintle wire depends on the channel size formed by the aligned interdigitating loops. The form, size, number and arrangement of the loops together with the dimension and structure of the pintle determine the ease and speed at which a seam will be joined. Increasing the diameter of the pintle requires increasing the diameter of the loops and possibly the fabric caliper in the seam area. The increased thickness may produce imperfections in the product or cause machine vibrations due to imbalance during running of the machine. Furthermore, seamed fabrics often experience other problems, including surface property variations, such as void volume and permeability, in the seam area. Surface property variations between the fabric and the seam area can cause undesirable marking on the paper product.
Various known seams utilize a joining wire or pintle which is inserted through seam loops at each end of the fabric to render it endless. Current pintles are made of standard monofilament, mechanically attached by a swedge to a lead wire. The wire is pushed through the interlocked loops and the monofilament cables of various size and number are pulled in to fill the loops. This process is adequate, but still leaves a looseness to the connection that allows the seam to separate. That separation results in the batt opening at the seam and creates a mark in the sheet. It also causes a noise at the vacuum box and can lead to premature seam wear.
Another type of known pintle expands to form protrusions to fill voids in the seam area. Although filling the voids reduces marking on the paper sheet, the pintle does not pull the ends of the fabric together. The pintle therefore must be inserted into a channel that is just slightly larger than the diameter of the pintle, if the seam is to be tight. This makes insertion of the pintle more difficult and time consuming.
An expandable pintle that pulls the fabric ends together to form a tight seam would be beneficial in solving the aforementioned problems.
The present invention is an expandable pintle for joining a seam comprised of a plurality of intermeshed loops at the end of a papermaking fabric to render the fabric endless. The pintle has an initial configuration which is smaller than the channel formed by the loops, and expands after insertion to create a tight connection.